Stirling-type pulse tube refrigerator and flow smoother thereof

ABSTRACT

A Stirling-type pulse tube refrigerator includes: a compressor which pressurizes and depressurizes a gas; a regenerator which is supplied with the gas from the compressor or supplies the gas to the compressor through pressurization or depressurization of the compressor; a pulse tube which is supplied with the gas from the regenerator or supplies the gas to the regenerator; and a flow smoother which is disposed on at least one of a high temperature side and a low temperature side of the pulse tube. The flow smoother includes a plurality of meshes arranged to be laminated and a holding member which maintains gaps between the plurality of meshes.

INCORPORATION BY REFERENCE

Priority is claimed to Japanese Patent Application No. 2013-106597, filed May 20, 2013, the entire content of which is incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a Stirling-type pulse tube refrigerator.

2. Description of the Related Art

There is a case where a Stirling-type pulse tube refrigerator (pulse tube refrigerator) is used as an apparatus for realizing a low temperature environment. In the pulse tube refrigerator, by repeating an operation of supplying a refrigerant gas compressed by a compressor to a regenerator and a pulse tube and an operation of recovering the supplied refrigerant gas by the compressor, the temperatures of the low temperature portions (for example, cold heads) of the regenerator and the pulse tube are reduced.

In the related art, in order to uniformize the velocity distribution of a refrigerant gas which flows from a regenerative tube (regenerator) to a pulse tube, or, from the pulse tube to the regenerative tube, a technique related to a pulse tube refrigerator having a wire mesh (flow smoother) disposed on the low temperature side of the pulse tube is disclosed.

SUMMARY

According to an embodiment of the present invention, there is provided a Stirling-type pulse tube refrigerator including: a compressor which pressurizes and depressurizes a gas; a regenerator which is supplied with the gas from the compressor or supplies the gas to the compressor through pressurization or depressurization of the compressor; a pulse tube which is supplied with the gas from the regenerator or supplies the gas to the regenerator; and a flow smoother which is disposed on at least one of a high temperature side and a low temperature side of the pulse tube. The flow smoother includes a plurality of meshes arranged to be laminated and a holding member which maintains gaps between the plurality of meshes.

According to another embodiment of the present invention, there is provided a flow smoother which is used in the above-described Stirling-type pulse tube refrigerator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram illustrating an example of a pulse tube refrigerator according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating the arrangement of a flow smoother of the pulse tube refrigerator according to the embodiment of the present invention.

FIG. 3 is a schematic exploded view illustrating the flow smoother of the pulse tube refrigerator according to the embodiment of the present invention.

FIGS. 4A and 4B are explanatory views illustrating an example of the flow smoother of the pulse tube refrigerator according to the embodiment of the present invention.

FIGS. 5A, 5B, and 5C are explanatory views illustrating a rectification effect of the flow smoother of the pulse tube refrigerator according to the embodiment of the present invention.

FIGS. 6A and 6B are explanatory views illustrating another example of the flow smoother of the pulse tube refrigerator according to the embodiment of the present invention.

DETAILED DESCRIPTION

In the technique disclosed in the related art, a plurality of wire meshes are laminated, and hence variations occur in flow paths formed due to the opening sizes of the wire meshes. Particularly, in a Stirling-type pulse tube refrigerator, the frequency of the operation of repeating the supply and the recovery of refrigerant gas is high (for example, 20 Hz or higher); hence, there may be cases where variations in the rectification effect of the flow smoother occur due to the variation in the flow paths formed by the plurality of wire meshes which are laminated.

It is desirable to provide a Stirling-type pulse tube refrigerator and a flow smoother thereof capable of reducing variations in the rectification effect of a flow smoother by arranging a plurality of meshes with gaps, thereby improving cooling efficiency.

The compressor may pressurize and depressurize the gas at an operation frequency of 20 Hz or higher. The Stirling-type pulse tube refrigerator may further include: a heat exchanger which is disposed on the high temperature side of the pulse tube; and a buffer tank which is connected on the opposite side to the pulse tube side of the heat exchanger, in which the flow smoother may be disposed on the heat exchanger side of the pulse tube. The holding member may be disposed in outer peripheries of the plurality of meshes. The holding member may be disposed at a center portion of the plurality of meshes. The holding member may interpose the plurality of meshes therein as one body. The plurality of meshes may have an opening portion at a center thereof, and the holding member may be disposed in the opening portion. The plurality of meshes may include a fine mesh and a coarse mesh, and the flow smoother may have the coarse mesh disposed on an outside of the fine mesh.

Exemplary embodiments of the present invention which are not limited will be described with reference to the accompanying drawings. In addition, in the descriptions of the entire accompanying drawings, like members and components are denoted by like reference numerals, and overlapping descriptions will be omitted. In addition, the drawings do not show a relative ratio between members or components unless so designated. Accordingly, specific dimensions may be determined by those skilled in the art according to the following embodiments which are not limited. Configuration of Stirling-type Pulse Tube Refrigerator

A Stirling-type pulse tube refrigerator and a flow smoother used in the Stirling-type pulse tube refrigerator according to an embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a schematic configuration diagram illustrating an example of the pulse tube refrigerator according to the embodiment of the present invention. The Stirling-type pulse tube refrigerator which may use the embodiment of the present invention is not limited to that illustrated in FIG. 1. In FIG. 1, a compressor 11 and a regenerator 12RG communicate with each other through an external heat exchanger (aftercooler) 12AC. However, the pulse tube refrigerator which may use the embodiment of the present invention may not include the external heat exchanger 12AC.

As illustrated in FIG. 1, a Stirling-type pulse tube refrigerator (hereinafter, referred to as “pulse tube refrigerator”) 100 according to the above-described embodiment includes the compressor 11 which allows a gas to flow through the inside of the pulse tube refrigerator 100, the regenerator 12RG which is cooled by the supplied gas, and a pulse tube 13 which is connected to the regenerator 12RG through a low temperature portion 12CH. The pulse tube refrigerator 100 includes a flow smoother 14 which is disposed on at least one of the high temperature side and the low temperature side of the pulse tube 13. Furthermore, the pulse tube refrigerator 100 includes a heat exchanger 15 which is disposed on the high temperature side of the pulse tube 13, and an inertance tube 16 t and a buffer tank 16 which are connected on the opposite side to the pulse tube 13 side of the heat exchanger 15. The pulse tube refrigerator 100 according to the embodiment of the present invention may use, for example, helium gas as the gas (refrigerant gas).

The pulse tube refrigerator 100 allows the gas (high-pressure gas) supplied from the compressor 11 to flow through the regenerator 12RG, the low temperature portion 12CH, and the pulse tube 13. In this case, the low-pressure gas which is present in advance in the pulse tube 13 is compressed by the high-pressure gas which flows therein. Therefore, the pressure in the pulse tube 13 becomes higher than the pressure in the buffer tank 16 such that the gas flows into the buffer tank 16 through the inertance tube 16 t. The pulse tube refrigerator 100 changes the phase relationship between the pressure change and the volume change in the gas by flowing the gas into the inertance tube 16 t and the buffer tank 16. The buffer tank 16 is a container having a greater volume than those of the other components.

Accordingly, the pulse tube refrigerator 100 causes the phase difference between the gas in the pulse tube 13 and the gas in the regenerator 12RG to absorb heat from the low temperature portion 12CH so as to interpolate the gap between the levels of energy consumed during adiabatic expansion of the gas from an isothermal state. That is, the pulse tube refrigerator 100 makes the low temperature portion 12CH cold. Subsequently, the pulse tube refrigerator 100 dissipates (releases) the heat (energy) absorbed from the low temperature portion 12CH using the heat exchanger 15 disposed on the high temperature side of the pulse tube 13.

As described above, the pulse tube refrigerator 100 may cool an uncooled object which is thermally connected to the low temperature portion 12CH by repeating the expansion and compression operations according to the adiabatic change in the pulse tube refrigerator 100. The pulse tube refrigerator 100 according to the embodiment of the present invention may pressurize or depressurize the gas at an operation frequency of 20 Hz or higher.

The compressor 11 allows the gas to flow through the inside of the pulse tube refrigerator 100. The compressor 11 (Stirling-type pulse tube refrigerator) according to the embodiment of the present invention allows the gas to flow through the inside of the pulse tube refrigerator 100 by pressurizing and depressurizing the gas using a cylinder and a piston which oppose each other and form a pair as illustrated in FIG. 1. Here, the piston may be driven (moved to reciprocate) using a drive mechanism (not illustrated) such as a magnet, a motor, or a cam.

The compressor 11 includes a pressure chamber formed between the cylinder and the piston which form a pair. The formed pressure chamber in the compressor 11 is connected to the regenerator 12RG. Accordingly, the compressor 11 can supply the gas to the regenerator 12RG by pressurizing the gas in the pressure chamber through the movement of the piston. In addition, the compressor 11 can be supplied with (recover) the gas from the regenerator 12RG by depressurizing the gas in the pressure chamber through the movement of the piston.

The regenerator 12RG is cooled by the gas supplied from the compressor 11 or the pulse tube 13. The regenerator 12RG may be configured to have, for example, a regenerative material (not illustrated) disposed in a tube member. As the tube member, for example, a hollow cylinder may be used. As the regenerative material, for example, a wire mesh may be used.

The regenerator 12RG allows the gas (compressed gas) supplied from the compressor 11 to undergo adiabatic expansion so as to reduce the temperature of the gas. The regenerator 12RG is cooled by the gas (gas having a comparatively low temperature) supplied from the pulse tube 13 (the low temperature portion 12CH). That is, the regenerator 12RG regenerates the coldness of the supplied gas.

The pulse tube 13 is a tube having a substantially cylindrical shape, and causes the phase difference between the gas therein and the gas in the regenerator 12RG. The pulse tube 13 is connected to the regenerator 12RG through the low temperature portion 12CH. The pulse tube 13 is supplied with the gas from the regenerator 12RG or supplies the gas to the regenerator 12RG through the low temperature portion 12CH as the gas is pressurized or depressurized by the compressor 11. In FIG. 1, an in-line type is exemplified as a type of connection between the regenerator 12RG and the pulse tube 13 of the pulse tube refrigerator 100. However, a U-shaped type may also be employed.

The pulse tube refrigerator 100 according to the embodiment of the present invention further includes the flow smoother 14 which is disposed in the pulse tube 13. That is, by using the flow smoother 14 which is disposed on at least one of the high temperature side (the inertance tube 16 t side) and the low temperature side (the low temperature portion 12CH side) of the pulse tube 13, the pulse tube refrigerator 100 uniformizes the velocity distribution of the gas which flows from the pulse tube 13 and the gas which flows into the pulse tube 13.

FIG. 2 illustrates an example of a schematic cross-sectional view illustrating the arrangement of the flow smoother of the pulse tube refrigerator according to the embodiment of the present invention.

As illustrated in FIG. 2, the flow smoother 14 according to the embodiment of the present invention is disposed, for example, on the high temperature side (the inertance tube 16 t side) of the pulse tube 13. Accordingly, the pulse tube refrigerator 100 can substantially uniformize the velocity distribution of a gas Fs which flows from the pulse tube 13 into the heat exchanger 15 (and into the inertance tube 16 t and the buffer tank 16) and a gas Fr which flows from the heat exchanger 15 (and the inertance tube 16 t and the buffer tank 16) into the pulse tube 13.

The pulse tube refrigerator 100 may use a heat exchanger in which slits are provided in a copper block as the heat exchanger 15 for cooling the gas. As illustrated in FIG. 2, the pulse tube refrigerator 100 may further use a water cooling type water jacket 15WJ (or air cooling type fins or the like) for cooling the gas.

FIG. 3 illustrates an example of a schematic exploded view illustrating the flow smoother of the pulse tube refrigerator according to the embodiment of the present invention.

As illustrated in FIG. 3, the flow smoother 14 according to the embodiment of the present invention includes a plurality of meshes 14 arranged to be laminated. Here, the plurality of meshes 14 are configured to include fine meshes 14 a and coarse meshes 14 b.

The flow smoother 14 which may use the embodiment of the present invention may use four or more sheets (for example, five to twenty sheets) of mesh. In addition, the flow smoother 14 may be configured so that a corresponding number of sheets of mesh appropriate to the diameter of the flow path or the flow velocity of the gas are arranged. Furthermore, as the plurality of meshes 14, a plurality of sheets of mesh having the same opening size may also be used.

As illustrated in FIG. 3, the flow smoother 14 may be configured so that, for example, the coarse meshes 14 b are arranged on the outside of the fine meshes 14 a. Accordingly, the flow smoother 14 can reduce turbulence which occurs during the flow of the gas into the flow smoother 14 using the coarse meshes 14 b, and can obtain a sufficient rectification effect using the fine meshes 14 a.

The mesh size of the plurality of meshes 14 being used may be, for example, #30 to #500 (for example, the opening size of the wire mesh is about 0.577 mm to 0.026 mm). The flow smoother 14 may use, as well as the wire mesh, a punching metal, a metal filter, a resin filter or a foam metal, a porous body which can be used as the flow smoother, or the like.

The flow smoother 14 according to the embodiment of the present invention further includes a holding member 14S (described later in FIGS. 4A and 4B or in FIGS. 6A and 6B) which maintains gaps between the plurality of meshes 14. The configuration of the holding member 14S will be described in the [Configuration of Flow smoother] described below. Configuration of Flow smoother

Examples of the flow smoother 14 of the pulse tube refrigerator 100 according to the embodiment of the present invention will be described with reference to FIGS. 4A to 6B. Here, FIG. 4A is a plan view illustrating an example (14A) of the flow smoother 14 according to the embodiment of the present invention. FIG. 4B is a cross-sectional view illustrating the flow smoother 14A. FIG. 5A is an explanatory view illustrating the rectification effect of the flow smoother 14A in a case of using the fine meshes 14 a and the coarse meshes 14 b. FIG. 5B is an explanatory view illustrating a rectification effect in a case of using meshes having the same opening size. FIG. 5C is an explanatory view illustrating a rectification effect in a case of laminating a plurality of meshes without gaps provided therebetween. FIGS. 6A and 6B are explanatory views illustrating another example (14B) of the flow smoother 14.

As illustrated in FIGS. 4A and 4B, in the flow smoother 14A (the pulse tube refrigerator 100), the holding member 14S includes a housing 14Sh, a stopper ring 14Ss, and a plurality of spacer rings 14Sp. Here, the holding member 14S (the housing 14Sh, the stopper ring 14Ss, and the plurality of spacer rings 14Sp) is disposed in the outer peripheries of the plurality of laminated meshes (14Ma and 14Mb). The holding member 14S holds the plurality of meshes (14Ma and 14Mb) by maintaining gaps.

The housing 14Sh is a member which holds the plurality of meshes (14Ma and 14Mb), the stopper ring 14Ss, and the spacer rings 14Sp. The housing 14Sh may use, for example, a substantially cylindrical member. In the housing 14Sh, the plurality of laminated meshes are arranged in the substantially cylindrical inner portion thereof.

The stopper ring 14Ss is a member which presses and fixes the plurality of laminated meshes (14Ma and 14Mb) and the spacer rings 14Sp. As the stopper ring 14Ss, for example, a bellows-shaped member may be used.

The plurality of spacer rings 14Sp are members which are arranged between the plurality of meshes (14Ma and 14Mb) to maintain the gaps between the plurality of meshes (14Ma and 14Mb). As the spacer ring 14Sp, for example, an annular (ring-shaped) member may be used. A diffusion bonding process is performed on the spacer rings 14Sp and the outer peripheries of the plurality of meshes to fix the plurality of meshes.

The “diffusion bonding process” is a method of bonding the interface between the mesh and the spacer ring by causing mutual diffusion of atoms at the interface of the mesh through heating. Accordingly, thermal contact properties at each of the interfaces are improved, resulting in a reduction in thermal resistance. The diffusion bonding process may be performed in a range of 800° C. to 1080° C. (for example, 1000° C.)

As illustrated in FIG. 5A, in the flow smoother 14A (pulse tube refrigerator 100) according to the embodiment of the present invention, since the positions of the plurality of meshes (14Ma and 14Mb) are fixed using the plurality of spacer rings 14Sp, the flow paths formed due to the opening sizes of the plurality of meshes can be accurately fixed (determined) into desirable flow path shapes. In the flow smoother 14A, as illustrated in FIG. 5A, the positions of the opening sizes of the plurality of meshes may be arranged to be sequentially shifted from each other.

Accordingly, the flow smoother 14A (the pulse tube refrigerator 100) according to the embodiment of the present invention can reduce variations in the flow paths formed due to the opening sizes of the plurality of meshes. In addition, since the flow smoother 14A according to the embodiment of the present invention can reduce variations in the flow paths formed by the plurality of laminated meshes, variations in the rectification effect can also be reduced. That is, the pulse tube refrigerator 100 according to the embodiment of the present invention can improve the rectification effect of the flow smoother 14A and easily control the flow rate (velocity) of the gas which flows therein, thereby improving the cooling performance of the refrigerator.

Furthermore, in the flow smoother 14A according to the embodiment of the present invention, since the plurality of meshes (14Ma and 14Mb) can be held by maintain the gaps using the holding member 14S, the plurality of meshes can be prevented from being brought into contact with each other. Particularly, in the Stirling-type pulse tube refrigerator, since the frequency of the operation of repeating the supply and the recovery of the refrigerant gas is high (for example, 20 Hz or higher), the plurality of meshes are easily damaged when coming into contact with each other. In the flow smoother 14A according to the embodiment of the present invention, since the plurality of meshes are prevented by the holding member 14S from being brought into contact with each other, damage to the meshes can be prevented.

Furthermore, as illustrated in FIG. 5B, in a case where meshes having the same opening size are used, variations in the flow path formed due to the opening sizes of the plurality of meshes can be reduced by using the holding member 14S (FIGS. 4A and 4B) according to the embodiment of the present invention similarly to FIG. 5A, and variations in the rectification effect of the flow smoother can be reduced.

In contrast, as illustrated in FIG. 5C, in a case where a plurality of meshes are laminated without maintaining gaps therebetween, there may be cases where variations in the flow path shape formed due to the opening sizes of the plurality of meshes occur. In addition, in the case where the plurality of meshes are laminated without maintaining the gaps therebetween, there maybe cases where variations in the fluid resistance occur due to the variations in the flow path shape formed due to the opening sizes of the plurality of meshes. That is, in the case where the plurality of meshes are laminated without maintaining the gaps therebetween (FIG. 5C), compared to the cases of FIGS. 5A and 5B, variations in the rectification effect of the flow smoother increase. In addition, in the case where the plurality of meshes are laminated without maintaining the gaps therebetween, since the variations in the rectification effect of the flow smoother increase, there is a concern that cooling performance may be reduced.

As illustrated in FIGS. 6A and 6B, a flow smoother 14B (the pulse tube refrigerator 100) includes the holding member 14S which is configured to include the housing 14Sh, the stopper ring 14Ss, and the plurality of spacer rings 14Sp similarly to the flow smoother 14A (FIGS. 4A and 4B). The flow smoother 14B further includes an opening portion 14Mw at the center of the plurality of laminated meshes (14Ma and 14Mb). The holding member 14S of the flow smoother 14B further includes a bolt member 14Sb and a plurality of second spacer rings 14Sp2.

The bolt member 14Sb is disposed in the opening portion 14Mw of the plurality of meshes (14Ma and 14Mb). The plurality of second spacer rings 14Sp2 are arranged between the plurality of meshes at the center of the plurality of meshes to maintain the gaps between the plurality of meshes. The housing 14Sh, the stopper ring 14Ss, and the plurality of spacer rings 14Sp of the holding member 14S are similar to those of FIGS. 4A and 4B, and thus the descriptions thereof will be omitted.

As illustrated in FIGS. 6A and 6B, the flow smoother 14B uses the plurality of second spacer rings 14Sp2 to interpose the plurality of meshes (14Ma and 14Mb) therebetween as one body. Therefore, the flow smoother 14B has a higher rigidity than the flow smoother 14A (FIGS. 4A and 4B). That is, the flow smoother 14B may have high mechanical strength, have a small deformation amount (for example, deflection amount) of the plurality of meshes, and further reduce variations (deformation) in the flow paths formed due to the opening sizes of the plurality of meshes and variations in the rectification effect. Since the flow smoother 14B can reduce the deformation amount of the plurality of meshes, damage to the plurality of meshes due to contact therebetween can be further prevented.

As described above, according to the Stirling-type pulse tube refrigerator 100 or the flow smoother 14 thereof according to the embodiment of the present invention, by arranging the plurality of meshes with the gaps provided therebetween using the holding member 14S, variations in the rectification effect of the flow smoother 14 can be reduced, thereby improving cooling efficiency. In addition, according to the Stirling-type pulse tube refrigerator 100 or the flow smoother 14 thereof according to the embodiment of the present invention, since the plurality of meshes are prevented from being brought into contact with each other by using the holding member 14S, damage to the plurality of meshes can be prevented.

It should be understood that the invention is not limited to the above-described embodiment, but may be modified into various forms on the basis of the spirit of the invention. Additionally, the modifications are included in the scope of the invention. 

1. A Stirling-type pulse tube refrigerator comprising: a compressor which pressurizes and depressurizes a gas; a regenerator which is supplied with the gas from the compressor or supplies the gas to the compressor through pressurization or depressurization of the compressor; a pulse tube which is supplied with the gas from the regenerator or supplies the gas to the regenerator; and a flow smoother which is disposed on at least one of a high temperature side and a low temperature side of the pulse tube, wherein the flow smoother includes a plurality of meshes arranged to be laminated and a holding member which maintains gaps between the plurality of meshes.
 2. The Stirling-type pulse tube refrigerator according to claim 1, wherein the compressor pressurizes and depressurizes the gas at an operation frequency of 20 Hz or higher.
 3. The Stirling-type pulse tube refrigerator according to claim 1, further comprising: a heat exchanger which is disposed on the high temperature side of the pulse tube; and a buffer tank which is connected on the opposite side to the pulse tube side of the heat exchanger, wherein the flow smoother is disposed on the heat exchanger side of the pulse tube.
 4. The Stirling-type pulse tube refrigerator according to claim 1, wherein the holding member is disposed in outer peripheries of the plurality of meshes.
 5. The Stirling-type pulse tube refrigerator according to claim 1, wherein the holding member is disposed at a center portion of the plurality of meshes.
 6. The Stirling-type pulse tube refrigerator according to claim 5, wherein the holding member interposes the plurality of meshes therein as one body.
 7. The Stirling-type pulse tube refrigerator according to claim 5, wherein the plurality of meshes have an opening portion at a center thereof, and the holding member is disposed in the opening portion.
 8. The Stirling-type pulse tube refrigerator according to claim 1, wherein the plurality of meshes include a fine mesh and a coarse mesh, and the flow smoother has the coarse mesh disposed on an outside of the fine mesh.
 9. A flow smoother which is used in the Stirling-type pulse tube refrigerator according to claim
 1. 